Lifting truck



a. QUAYLE LIFTING TRUCK Jan. 9, 1945;

Filed Feb. 8, 1941 3 Sheets-Sheet 1 INVENTOR iaeaf 0mm:

BY I

ATTORNEY Jan. 9, 1945. s. QUAYLE LIFTING TRUCK Filed Feb. 8/1941 3 Sheets-Sheet 2 Y 4 Y Z w N R E, 0 Ne w ...m A

' Jan. 9, 1945.

ca. QUAYLE 2,367,051

LIFTING TRUCK Filed Feb. 8, 1941 3 Sheets-Sheet 3 INVENTOR [II-MIMI! 6:0865 004: t\ Q Q w BY N w 3% flAW ATTORNEY Patented Jan. 9, 1945 UNITED STATES PATENT OFFICE 2,367,051 1 i LIFTING TRUCK George Quayle, Philadelphia, Pa., assignor to The Yale 8: Towne Manufacturing Company,

Stamford, Conn a corporation of, Connecticut Application, February 8, 1041, Serial No. 378,003

20Claims. .iCl. 254-10) This inventionrelates to an industriallift truck of the type having a main frame or: lifting head, an elevating frame mounted for lifting movement relatively to said main frame orlifting head, and lifting means for lifting'said main frame relatively to said lifting head, My inventionwilLin this application be described as. embodied in. a truck of the" type disclosed'inthe Stuebing Patent No. 1,785,368, which is owned by The Yale. 81 Towne Manufacturing Company; the owner of this invention.

' mitted through, a yieldingmediumwhich is desirable in lifting manytypes of loads, and that similarly, the load will be held elevated by the same yielding medium.

As a further feature of my invention, the elevating frameis elevated by a lifting element which is part of the lifting meanspreferably car-- i ried on the main frame or lifting head. In the particular truck to which my invention is applied, the lifting element is preferably in the form of alifting link. It is a function of this lifting link to maintain th elevating frame in a lifted position until the. lifting link is itself, released,.whereupon the lifting link moves with the elevating frame into its lowered position. 'Since the lifting 'link itself lifts the elevating frame througha spring, hereafter called a lifting spring, it will be appreciated that it will therefore hold the elevating frame inany lifted position through the same spring. Because of this relationship of the parts, when theload is transported with the elevating frame in a lifted position, shocks.

received by the main frame will be absorbed by the lifting spring interposed between the lifting mechanism and the elevating frame. It is obvating frame, So. that when the load is transferred from the lifting. link of the liftin mech anism to the dashpot, the load will be supported by the dashpot through the medium of the spring. It will be appreciated that the shocks incidental to lowering will therefore-be cushioned by the spring, and that such action is extremely desirable.v It is affurther feature of the invention that the spring absorbs whatever play or looseness develops in the several parts, all as will'be set forth presently.

vious that this contributes easy riding to the load on the elevating frame, which is an extremely' desirable condition in many industries in which trucks of the particular class are used.

For controlling the lowering of the elevating frame, there is utilized a dashpot which is secured at one end to the main frame, and at itsot-her end relatively to the elevating frame. It is a featureof my invention that the end of the dashpot which is secured to the elevating frame is secured through the medium of a spring, pref-.

erably the lifting spring used in lifting the ele-.'

As a more detailed feature of .my invention, I utilize means. to control the lifting and lowering of the elevating frame and the action of the lifting spring, these means being in' the preferred form what'I term a control cam. Preferably, the control cam is connected to the lifting link for actuation-thereby to elevate the frame, and is preferably movable as by rotation relatively to the elevating frameto compress-the lifting spring, after which it moves bodily with the elevating frame as the lifting link is operated by the lifting means. 'It is, of course, through the lifting link and the control cam'and lifting spring, that the elevating frame is held in a lifted position.

The control cam ispreferably connected to the dashpot through what I term struts, whereby to extend the dashpot on lifting movement of the elevating frame, and whereby the dashpot controls the lowering movement of the elevating frame. It isa function of the spring and control cam to take up all play in'thedashpot, and in the various linkages at the time that the lifting was actually removed from the dashpot so that there was play in the dashpot amounting to approximately five-eighths of an inch. This play was taken up by the spring action immediately upon the release .of'the lifting link for lowering movement, so that the dashpot accepted the load and there was no shock thereto. The extreme value of this constructionwilLof course, be fully appreciated'by those skilled in the art who will understand'the significance of the problem which has been met and solved.

One preferredform of the means which I have devised, is shown in the accompanying drawings,

and will be described in this specification, but it should be understood that I consider my invention to be a relatively broad one, and that I expect to obtain claims which will prevent the utilization of my contribution to the art in physi-. cal forms other than that herein shown and described. Also, while in describing one form of my invention I shall particularly point out what I now believe is the theory of operation thereof, I do not intend m invention to be limited in scope by that theory.

Referring now more particularly to the drawings wherein is shown a preferred form of my invention, Fig. 1 is a plan view looking down on the truck in which my invention is embodied. Fig. 2 is a side view of the truck of Fig. 1. Fig. 3 is a section taken along lines 33 of Fig. 1. Fig.

' 4 is a View similar to Fig. 3, but showing certain brackets 30 and bores 31a in the brackets S I. The front links 29 through which the elevating frame is mounted for lifting movement relatively to the main frame, are pivoted at their upper ends to the elevating frame through the said link shaft 32.

Mounted also on the shaft 32 and between the inner brackets 3|, is what I term a control cam assembly, designated generallyby the reference numeral 33 and shown best in Fig. 8. This con trol cam assembly 33 includes what I term a pair of control cams 34 assembled as by welding to the ends of a tube 35. It further includes a pair of ears 36 spaced from the control cams 34 and alsosecured as by welding to the tube 35. The controlscams 34 are bored as at 34a for pivotal mounting on the link shaft 32, as is clearly ilof the parts in different operating positions. Fig,

5 is a view taken along lines 55 of Fig. 2. Fi 6 is a perspective View of the parts of Fig. 5. Fig. 7 is a view looking downwardly on the saddle of the elevating frame showing it in its position of Fig. 3. Fig. 8 is a view looking downwardly on the control cam assembly in its position of Fig. 3.

Referring now more particularly to the drawings, the truck to which my invention is shown applied is, as I have already indicated, shown and described fully in the Stuebing Patent No. 1,785,368. It will, of course, be appreciated that the invention may be applied to other types of trucks, if so desired. Referring now more particularly to Figs. 1 and 2, the truck embodies a main frame l formed of side bars II and I2, and

to steer the front wheels H,

For the purpose of this invention, it is merely necessary to consider that when the lifting handle I6 is swung vertically, it actuates the lifting mechanism shown in dotted lines in Fig. 2 and including a pawl.|8. The pawl I8 is moved on a pivotal mounting for rotating th lifting ratchet I9 formed integrally with a pair of liftin crank arms 20, there being one crank arm extending outwardly of the lifting head l at each side The crank arms are held in any by a foot treadle 22. A depression of the foot treadle 22 effects the movement of the holding pawl 2| out 'of engagement with the lifting ratchet I9 to allow a lowering movement of the crank arms 20. It is thought that this description of the lifting head and its operation is all that is necessary for an appreciation ofthe invention, since for a further detailed disclosure,

reference may be had to the Stuebing patent.

" The elevating frame is designated generally by reference numeral 23, and comprises side bars 24 and 25 connected at their rear by a cross member :26, and at the. front end by what is termed in the art a saddle 21. The elevating frame 23 is pivoted to the mainframe throu h a rear link 'lustrat ed in Figs. 3-6, inclusive. The extreme lower ends of the control cams 34 are bored as at 3-1. for the passage of pivot pins 38, and through means of the pivot pins 38, each of the control cams is pivotally secured to what I term a lifting link 39, Each lifting link 39 is bifurcated as at 40 whereby to be secured through a pin 4| to one of the crank arms 2|]. It will therefore be appreciated that a clockwise movement of the crank arms 20 incidental to the lifting operation of the lifting mechanism within the lifting head |5, will effect a counterclockwise rotation of the control cam assembly 33 about the link shaft 32.

For resist ng this rotation of the control cam assembly, I utilize a pair of springs 42, each of which is housed within a tube 43 pivoted at 44 to the elevating frame 23. Mounted within each of the tubes 43 and traversing the center of the spring therein, is a rod 45 having a spring compressing disk 46 acting against the extreme left hand end of the spring 42. The other end of each rod 45 is adjustably secured to what I term a spring link 41. which is bifurcated at 48 whereby to be secured to a control cam 34 through the pin 38.

It is obvious that if the crank arms 20 are now rotated in a clockwise lifting direction, the control cam assembly will be rotated in a counterclockwise direction a degree depending on the load which is to be lifted by the elevating frame. Thus, with little or no load, the springs 42 will prevent any rotation whatsoever of the control cam assembly '33 on link shaft 32, so that the control cam assembly will move as a part of the elevating frame 23, through lifting movement of the lifting links 39.. When a comparatively heavy load is placed on. the elevating frame, it is obvious that the springs 42. must be compressed a degree sufficient to compensate for the weight of the load, and

that during this compression, the control cam assembly is rotated somewhat on shaft 32. Thereafter, the springs 42 remain compressed and the control cam assembly moves bodily with the ele- ,vating frame as the crank arms 20 and the lifting .links 39move in a lifting direction to move the elevating frame from its position of Fig. 2 to its It is obvious that the load is,

springs 42,.which may therefore be called lifting springs. 5

Moreover, since the elevating frame is maintained in a lifted-position through the use of the holding pawl 2| illustrated in Fig. 2, it is obvious .that the elevating frame is held in all lifted positions through the intermediary of the springs t2. Therefore, if the truck is transported over a relatively rough terrain, shock will be transmitted to the lifting frame only through the springs 42,

. frame and the load thereon.

earlier in the specification, I have actually tested o. truck embodying the construction herein set forth, in; which therewas a clear space of fiveeighths of. an inch below the plunger of the dashasst-non compressed to a considerable degree.

. It should he noted that each of the control cams has asurface '50 which is adapted .to impinge against a surface We of the saddle 21, shou'ldthe springs '42 fail to function, as through breakage,

or weakening, or in any other manner. Thus,

should the springs ,"42 fail for-any reason, the cani assembly 33 will rotate until the surfaces B eontact the surface 50s. Thereafter, the control earn assembly and the elevating frame will be actuated as a single unit by the lifting links 39 in a liftin .direction.

Y Referring now once again to Figs-7 and 8;, taken in conjunction with Figs. 3--6, the control earns 34 have bores ill in alignment with bores =52 formed in the ears 86 of the control cam assembly 33. As is best illustrated in Fig. 5, pivot shafts 53 extend through the bores 5| and 52 and through bores formed inthe lower ends of vertical struts 54. Each of the struts 54 is'pivoted through a pin 55 to a further vertical strut 55 and tea guide lever 51. There are, thus, twoguidejlevers 51, each of which is pivoted at 59 to the lifting head [5, it being the function of guide levers 5! to guide thestruts 54. 55 in a particular path, all as will be quite clearly indicated hereinafter.

The upper ends of the struts 56 are secured to a tube 6|, to'which in turn is secured a block 82. This block 62 forms the end of a plunger 63 of a hydraulic check or .dashpot assembly 64, The

"lower end of this dashpot assembly is pivoted througha shaft 65 to plates 65 which are welded as at 67 to the lifting head of the truck. In

effect, therefore, the dashpot extends between the main frame and the elevating frame, through the intermediary of the control cam assembly 33, and therefore, through the intermediary of the springs 12. It is obvious therefore, that when the load 'is'transferred to the dashpot through the release of the crank arms by the-pawl 2|,the lowering of the .load will be controlled by the dashpot through the struts 54, 5B, the control cam assembly 33,'and-the springs 42.

fore,- the lowering is through the intermediary of the springs 42. v

Moreover, it will be readily appreciated that "withthe load on the elevating frame lifted as in the position of Figs. 3 and 4, should the holding i pawl 2 I be released, the springs will act immjediately to move the rods 45 toward the left-in Figs. Band 4. This will move the spring links d'l'toward' the left, and will cause an immediate rota- .tion of the control cam assembly '33 sufiicient to absorb any play between the spring links 51 and the control cams 34, and between the control "cam assembly andth'e struts 54,. 5S, and such play as may have developed within the dashpot in; itself.

Thus, for example, should there be a leakagein the dashpot assembly so that there is no'oil opposing the drop of the plunger 53 for some distame, the compressed springs 42 will expand and rapidly pick up that distance, thereby preventing the transmission of the shock to the elevating As I indicated Functionallyqthera pct. This'space wastaken :up by the actionof the springs '42, so thatno shock was transmitted to the elevating frame'and the load.

WhileI believe that .I have fully described my invention, it may be helpful to review one complete liftlngand-lowering operation in order to more fully emphasize the coaction of the various parts.

A downward vertical swinging movement of the lifting handle 1'6 will effect a lifting rotation of the crank arms and the lifting links 39., whereby to rotate the control cam assembly of Fig." 8 a distance necessary to compress the springs 42 sufficiently to compensate for the load on the elevating frame. Thereafter, the control :cam assembly will be. moved bodily with the elevatingframe by the links-39 to elevate the load from the position of Fig. 2 to the position of Fig. 3. -Should shock be transmitted' to the elevating frame, the elevating frame willmove from the dot and dash position of Fig. 4 to its full line position, momentarily more fully compressing the springs 42.

i As the elevating platform is lifted-the control cam assembly 33' acts through the struts 54 and to move the plunger 63 of the dashpot assembly from the position of Figs. 2 and 5 to the position of Fig. 3, where the dashpot is ready to check the loweringmovement of the elevating frame. If the treadle 22 be now depressed to move the holding pawl 21 out of holding relation to ratchet 120, the crank arms 20 will move from the position of Fig. 3 towards the position of Fig. 2 allowing a lowering movement of the elevating frame.

Should there be any play in the linkage mechanism or leakage of fluid in the dashpot, upon release of the crank arms 20 the springs 42 will operate immediately to absorb that'play and to move the plunger 63 down into the dashpot until the liquid therein is encountered. This prevents a. transmission of shock which would take place were the elevating frame allowed to'dropthe distance required to absorb the play in thelinkage'andin the dashpot. This play is, of course, taken up through the rotation of'the control cam assembly'33 relatively to the elevating frame under the influence of the springs 42. Thereafter, there is a gradual lowering of the elevating frame under the c'ontrol of the dashpot, as is standard in this art.

I new claim: 1. In a truck of the class described, a main frame, an elevating frame mounted for upward lifting movement relatively to said main frame,

lifting mechanism on said main frame comprising a lifting'link,-a spring through the intermediary of which said link is connected to said elevating frame to lift said elevating frame through "the intermediaryof said spring, a control member movably mounted on said elevating frame. and connected to said link for guiding said link as it moves to lift the elevating frame, a 'dashpot, and means connecting said dashpot to said control member for controlling the lowering ing a lifting link, a spring between said link and the elevating frame through which said link lifts said frame, holding means for holding the lifting mechanism in a lifted position, and whereby said elevating frame is heldin lifted position through armour take up anyplay in the dashpot'and'm itscorfnectionstasaidframese I Imatruck of? the-class described-.amain frame, arr elevating framemounted for" lifting movement relatively thereto, lifting meansforlifts ing said elevating; frame; a dashpot secured at one when said elevating frame is supported by said dashpot through said means and control oamz 11. In a truck of class-described, armaizn frame, an elevating frame; mountedfer lifting movement relatively theretoa: dashpot secured at oneend to said frame? C ontro'lcam control cam rotates relatively to said elevating frame, and to lift the elevation frame when said spring resists further pivotal movement of said control camrelatively tosaidi elevating frame, means for: holding said: lifting link in predetermined positions corresponding to certain lifted positions of said;- elevating. frame, a hydraulic dashpot secured atone end tosaid mainframe, a-strut connecting the; other end of said dash. pot tosaid control cam whereby saidcontrol cam in its rotation relatively to said elevating frame and in its movement with: said elevating frame; extendszsaid dashpot when; said control cam is actuated to lift the e-levatirig, frame, and through said. dashpot: controls th lowering. of the elevating frame; I

15. In a truck of the class described, a main frame, an elevating frame mounted for upward pivoted on said elevating frame, aspring for re:

sisting pivotaL movement of saidI oontrol ycam relatively to said elevating, frame, a strut-scour ing; the other endof. said dashpot ta -said control j cam, whereby the said-zspringis under compression when said elevating frame is supported byzsaid dashpotthrougirsaid strut and control cam, lifting means on said main frame for lifting said elevating frame, and means of connection between said lifting means and said control cam for lifting said elevating frame by first rotating the control cam to placethe spring under compression and then moving said control cam and elevating frame together.

12. In a truck of the class described, a main frame, an elevating frame mounted for upward lifting movement relatively to said main frame, lifting mechanism on said main frame comprising a lifting element, a control cam pivoted on said elevating lframeandpivotally connected to said lifting element, a spring for resisting rotation of said control cam relatively to said elevating frame, whereby movement, of said lifting element actuates said control cam to compress said spring as said control cam rotates relatively to said elevating frame, and to lift the elevating frame when said spring resists further pivotal movement of said control cam relatively to said elevating frame.

13. In a truck of the class described, a main frame, an elevating frame mounted for upward lifting movement relatively to said main frame, lifting mechanism on said main frame comprising a lifting element, acontrol cam pivoted on said elevating frame and pivotally connected to said lifting element, a spring for resisting rotation of said control cam relatively to said elevating frame, whereby movement of said lifting element actuates said control cam to compress said spring as said control cam rotates relatively to said elevating frame, and to lift the elevating 7 frame whensaid spring resists further pivotal .ing a lifting link, a control cam pivoted on, said elevating frame and pivotally connected to said lifting link, a spring for resisting rotation of said control cam relatively-to said elevating frame, whereby movement of said lifting link actuates said control cam to compress said spring as said lifting'movement relatively to said main frame, lifting mechanism on said main frame comprising a, lifting link, a control campivoted-orr said elevating frame and pivotally connected to said lifting link, a spring for resisting; rotation of saidwcon-trol: cam relatively to said elevating frame,:whereby' movement of said lifting link actuaztes said; control; to compress? said spring as said control cam rotates relatively to said elevating frame, and to lift the elevating frame when said spring resists further pivotal movement of, said control cam relatively to said elevating frame, means for holding said lifting link in predetermined positions corresponding to certain lifted positions of said elevating frame, a

hydraulic dashpot secured at one end to said main frame, a strut connecting the other end of said dashpot to said control cam whereby said control cam in its rotation relatively to said elevating frame and in its movement with said elevating frame, extends said dashpot when said control cam is actuated to lift the elevating frame, and through said dashpot controls-the lowering of the elevating frame, the spring serving to move the control cam to take up any play ing pivotal movement of said control cam relatively to said elevating frame, lifting means on said main frame for lifting said elevating frame, and means of connection between said lifting means and said control cam for lifting said elevating frame by first rotating the control cam to place the spring under compression and then moving said control cam and elevating frame elevating platform relatively to said main frame,

and lifting means on said main frame for imparting lifting movement to said spring stressing link. 18. In a truck of the class described,v a main frame, an elevating frame, means mounting said elevating frame for upward lifting movement relatively to said main frame, a lifting'member pivoted on said elevating frame, a spring stressing link mounted for endwise movement relatively to said lifting member and for pivotal movement therewith, a spring between said link and lifting member through which said spring stressing link actuates said lifting member to lift said elevating platform relatively to said main frame, lifting means on said main frame for imparting lifting movement to said spring stressing link, and guide means for maintaining said liftin member and spring stressing link against free pivotal movement relatively to said elevating frame as said link is actuated by said lifting 19. In a truck of the class described, a main frame, an elevating frame, means mounting said elevating frame for upward lifting movement relatively to said main frame, a lifting member pivoted on said elevating frame, a spring stressing link mounted for endwise movement relatively to said lifting member and for pivotal movement therewith, a spring between said link and lifting member through which said spring stressing link actuates said lifting member to lift said elevating platformrelatively to said main frame, lifting means on said main frame for imparting lifting movement to said spring stressing link, and guide means for guiding said lifting member and spring stressing link in their pivotal movement relatively to said elevating platform as said link is actuated by said lifting means to lift said elevating platform,

20. In a truck of the class described, a main frame, an elevating frame, means mounting said elevating frame for upward lifting movement relatively to said main frame, a lifting member pivoted on said elevating frame, a spring stressing link, means mounting said link for movement relatively to said lifting member and for movement with said lifting member relatively to said elevating frame, a spring between said link and lifting member through which said spring stressing link actuates said lifting member'to lift said elevating platform relatively to said main frame, and lifting means on said main frame for imparting lifting movement to said springstressing link.

GEORGE QUAYLE. 

